Prediction and planning are important aspects of behavior that involve computations performed in prefrontal cortex. Visually guided behavior generally occurs in a dynamic environment where objects in motion may be temporarily occluded by other objects. The ability to predict the future location of a moving target is important for controlling voluntary movements. Humans and monkeys are able to extrapolate target motion fairly accurately even when the target is rendered temporarily invisible. This ability may depend on attention and working memory interacting to maintain a dynamic mental representation of the invisible target. Because prefrontal cortex is involved in working memory, planning, and eye movement control, and also receives afferent projections from motion processing areas in visual cortex, we are motivated to investigate the role of prefrontal cortex in trajectory estimation. We plan three experiments to investigate the internal representation of target motion during trajectory estimation. First, we will use micro-stimulation to probe the updating of saccade plans during invisible target tracking. Second, we will perform quantitative visual receptive field mapping to track the locus of spatial attention during the task. Finally, we will use a match/non-match paradigm to determine if prefrontal neurons respond differently to predictable versus unexpected target motions. These experiments will shed light on the interaction of attention and working memory for short-range prediction.